I am a 19 year old boy and my sister is 21. I first found her sexually attractive about four years ago. I'm not sure how it happened. But I've had fantasies about her ever since. If it adds any insight, here's some more info: we've always lived in the same house up until a few months ago. We have always been close even though we don't really show it. Even though I rarely tell her about things in my life, I know that I always can. Any sincear input will be apreceated. Thanks!